Page 264 - Rock Mechanics For Underground Mining

EXCAVATION DESIGN IN BLOCKY ROCK

(a)

(b)

Figure 9.4 (a) Vertical cross-section plane 1, outside the circle for plane 2 and inside the circle for plane 3. The triangle is
through a reference sphere, showing therefore denoted 010.
upper hemisphere stereographic pro- The eight spherical triangles of Figure 9.6 correspond in three dimensions to the
jection of points on the upper and
lower hemisphere; (b) a complete up- plane angle U 1 L 2 for the two-dimensional case in Figure 9.3. The rock prisms they
per hemisphere stereographic projec- represent are the joint pyramids of the blocky rock mass.
tion of planes intersecting both upper
and lower hemispheres.
The Excavation Pyramid (EP). As shown for the two-dimensional case in Figure 9.3,
the excavation pyramid EP represents the rock on the solid side of the planar surfaces
of the excavation. In three dimensions, for a single planar excavation surface oriented
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